Electrolyte solution for high-capacity lithium-ion battery, preparation method and lithium-ion battery

Abstract

The invention discloses an electrolyte solution for a high-capacity lithium-ion battery. The electrolyte solution includes non-aqueous solvent, lithium hexafluorophosphate, negative electrode film forming additive, positive electrode surface activity inhibiting additive and transition metal ion complexant; the negative electrode film forming additive includes organic ester negative electrode film forming additive of 1 to 10wt% of the total electrolyte solution and inorganic lithium salt negative electrode film forming additive of 0.5 to 2wt% of the total electrolyte solution; the positive electrode surface activity inhibiting additive includes fluorinated ether additive of 1 to 5wt% of the total electrolyte solution and nitrile additive of 0.1 to 5wt% of the total electrolyte solution; the transition metal ion complexant is of 0.1 to 1.0wt% of the total electrolyte solution. The electrolyte solution is adaptive to the high-capacity lithium-ion battery and is capable of optimizing the circulating performance and high-temperature storage performance of the lithium-ion battery. The invention further provides a preparation method of the electrolyte solution and the high-capacity lithium-ion battery adopting the electrolyte solution.

Description

technical field [0001] The invention relates to the field of electrolytic solutions, in particular to an electrolytic solution for high-capacity lithium-ion batteries, a method for preparing the electrolytic solution, and a lithium-ion battery using the electrolytic solution. Background technique [0002] Lithium-ion battery has been a research hotspot in the field of new energy since it came out in 1999. It is widely used in electronic products such as mobile phones, digital cameras and notebook computers due to its advantages of high voltage, large capacity, no memory effect and long life. In addition, lithium-ion batteries are also directly applied to electric vehicles and hybrid electric vehicles as energy storage devices for alternative energy sources. With the development of technology, the requirements for the energy density of lithium batteries are getting higher and higher. [0003] Among the most commonly used positive electrode materials at present, when the nic...

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Problems solved by technology

[0006] In a lithium-ion battery system in which the high-nickel material is the positive electrode and the silicon-carbon composite material is the negative electrode, due to the increase of the Ni content in the high-nickel material, and during the charging process, with the increase of the charging voltage, the Ni on the surface of the high-nickel material positive electrode 3+ and Ni 4+ content increased due to the Ni 4+ It has strong oxidizing properties, not only reacts with the electrolyte, destroys the function of the electrolyte, but also may cause the cathode material to decompose and release O at a lower temperature. 2 , generate a lot of heat, and the electrolyte decomposes under high temperature conditions to generate a lot of gas, which brings safety hazards to the battery

The dissolution of transition metal ions from the positive electrode of high-nickel materials deposited on the negative electrode will damage the SEI film of the negative electrode and cause deterioration of battery performance.

Although the silicon-carbon composite negative electrode has a high specific capacity, due to the huge volume effect of silicon in the process of lithium intercalation and deintercalation, the SEI film on the surface of the negative electrode is continuously destroyed and regenerated, and at the same time, the silicon particles are broken or pulverized due to huge stress. , causing the active material on the silicon negative electrode to fall off, and the electrical contact between the active material and the current collector deteriorates, resulting in an increase in the internal resistance of the battery and poor battery performance

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